This invention relates to mine stoppings, and in particular to a contractible mine stopping adapted to accommodate the convergence of the floor and roof of a passageway.
So-called mine "stoppings" are widely used in mines to stop off flow of air in passages in the mines, a stopping being generally installed at the entrance of a passage to block the flow of air therethrough. A problem encountered with at least some of the prior art mine stoppings is the loss of structural integrity of the stopping upon the vertical convergence of the floor and roof of the passageway when there is a shifting and heaving of the mine in the vicinity of the passageway. Such temporary shifting and heaving can cause permanent deformation of the stopping, resulting in the creation of air gaps between the stopping and the passageway, and defeating the air-blocking function of the stopping. Furthermore, even where the convergence is permanent, the stoppings can deform so much under the compressive load that the stopping loses its structural integrity causing air leaks, and potential failure of the stopping.
It is believed that certain prior art mine stoppings have incorporated a yieldable material (e.g., expanded polysterene plastic) in an attempt to resolve the aforementioned problem, but such material is not fireproof, which presents a serious problem.